Ironmaking Processors That Saved the Consett Ironworks During the Next Twenty Four years In Operation 1864 to 1888
Chapter Two
Ironmaking Explained
Ironmaking processors, In entering upon more minute detail of the various processors carried on at these works. From the preparation of material for the blast furnace to the Manufacture of iron and steel into a miscellaneous description of articles, will not be deemed out of place. Indeed it will assist the general reader, too, first of all, devote a few remarks to a history of the Manufacture of iron.
Uses
Every person ought to know the various uses of this truly precious metal. It is capable of being: 1/ cast into moulds of any form; 2/ being drawn out into wire of any desired length, 3/ extended into plates or sheets; 4/ being bent in every direction; and of being sharpened, hardened, or softened at pleasure.
Iron accommodates itself to all our wants, to all our desires, and even to all our caprices. It is equally serviceable to the arts, to the sciences, to agriculture, and war. The same ore furnishes the ship’s anchor, the sword, the ploughshare, the scythe, the pruning hook, the locomotive, the needle, the graver, the spring of the watch and the carriage, the chisel, the chain, the anchor, the compass, the cannon, and the bomb. It is a medicine of much virtue, and the only metal suited to the humane frame.
The ore of iron is scattered all over the globe. The person who first made known the use of metal should be known as the father of Arts, and the author of plenty. Though, slow was the advance made in the development of its various properties, how gigantic now, are products produced!
The History Of Iron
Let us for a few minutes glance at its history in this country. A writer of some eminence on iron manufacture observed. That time was when the processes necessary to the production of good iron were carried on by guesswork or by “main-strength.”
In the year 1740, iron manufacturers of England may be said to have been in a state of comparative infancy. Indeed the same remark will apply to most of the manufactures of England of that period. Little more than a century ago. Though “at what time the manufacture of iron began in this country”, says Chambers in his Information. “There was no means of ascertaining. Ironworks were said to have been established by the Romans in the forest of Dean in Gloucestershire. Be this as it may, it was not until a comparatively recent period that the Manufacture began to assume anything like national importance.
The Usage Of Wood
Down to the seventeenth century, we quote now from the Cyclopaedia of Commerce. (The ore was entirely smelted with charcoal. There was a considerable number of furnaces in those districts where wood and iron ore were plentiful. Particularly the Weald of Kent, Surrey, and Sussex).
Over time, wood fuel was becoming scarce. As a result, the process of ironmaking became threatened.
Many attempts to retard the decline of the use of pit coal but without effect. The simple hand worked bellows or the more powerful water movement, which produced a sufficiency of blast for charcoal. This had little impact on coal. The number of furnaces which in 1610, was estimated by Lord Dudley at 136, fell off towards the middle of the eighteenth century to 59.
Ironmaking Rescued By Science
Science, however, came to the rescue of one of our most significant staple manufacturers. In 1760, Smeaton erected a cylinder blasting machine for the Carron Company (Scotland). Which, after some improvements, enabled the same furnace that formerly yielded ten or twelve tons weekly, to produce forty tons of manufactured iron. Shortly after this, Watts’ development of the steam-engine. Its application to the Consett Ironworks, not only revived the trade but enabled us to distance all foreign competition.
Ores that were not profitable, because of their inherent intractableness, of metal they contained. Were now advantageously submitted to the furnace and more metal is extracted from the wealthiest ores.
Various improvements also took place in the Manufacture of bar-iron, particularly by substituting machinery for hammering by hand labour. Then followed Mr Cort’s invention of “puddling” (1783). The high distinction of coal made the iron. Also Cort’s patent (1784) for rolling metal. With these inventions/innovations, some people called them. These gave way to significant improvement in the construction of the furnaces and ironmaking.
Iron Quantities On The Rise
Of recent comparative inventions, by far the most important is the substitution of hot for cold blasts. The art of artificially heating the air impelled into the furnaces. This discovery, made by Mr Neilson, of the Clyde Iron Works. Has the recommendation of obtaining a larger quantity of metal with a less degree of fuel. Whereas the cold air blast required 8 tons 1 cwt. Of coal to produce one ton of iron. A ton of iron is now produced by hot air blast with less than 2 tons of coal. “The result of these improvements and inventions,” says Chambers, “presents the statistician with some of the most astonishing facts in the history of British manufacturers”. In 1770 the quantity of iron made in the United Kingdom did not exceed 25,000 tons.” In
1795 it rose to 124,879 tons
1802 it rose to 170,000 tons
1828 it rose to 702,584 tons
1839 it rose to 1,512,000 tons
1847 it rose to 2,000,000
At present, when the iron is so rapidly superseding wood in shipbuilding, it may not be exaggerating to say that the amount of its annual ironmaking reached 3.500,000. With these preliminary remarks, we proceed to a continuation of these trends.
A Description Of The Derwent Iron Works
As you enter the Derwent Iron Works from Puddlers Row, there is a double line of railway. One line considerably elevated over the other; the higher for conveying iron ore to the calcining kilns, of which there is a long row; and the lower rail for bringing coal to the coke-ovens, of which also there is a significant number, and a further lot at Crook Hall.
Coke Manufacturing
The Manufacture of coke by the Company, it will be readily conceived, is a significant saving to the firm, who otherwise would have to purchase off the coke manufacturers. The mention here of the coke burning merely incidental; the Manufacture of coke being well known as to require no lengthened detail. The calcining process, however, is one to which we may devote a few words. We would mention, that the plain statement which you may receive from the workmen as to the reason for calcining the iron ore is substantially following the scientific explanation of scientific, educated writers and practical upon the subject.
Workmen at Derwent Iron Works will tell you The calcining kiln is where the ore is put and heated for two to three days until the kiln attendants are satisfied that the process has been sufficiently prolonged. The object of roasting the ore is to cause the water found in it, to evaporate, and at the same time to dispossess the stone of superabundant gases.
The Composition Of Iron Ores
Now turn to the scientific account, by Mr Samuel B. Rogers: – “Iron ores are as various in their natures as anything well to imagine. As a general rule, however, we may put them down as compounds of iron, oxygen, silex, alumine, lime magnesia, sulphur, carbon and water.” These ores yield in the smelting furnace from 30 to 42 per cent. of iron, with, from 15 to 30 per cent. of silex, and from 15 to 26 per cent. of water. Calcination removes the water from the ore in the kilns.
They’re also frequently found attached to these ores crystals of per-sulphuret of iron, a material that would be particularly dangerous in the blast furnace. The quantity of these crystals, however, is generally minimal. A thorough roasting drives off the sulphur content. At the same time that their water of composition evapourates
Education Of The Workforce
Mr Rogers’s remarks, in another part of his work. On the advisability of ironmasters educating their men in the scientific part of their profession. Urging very correctly, no doubt, that science in this matter has cast out and assumed the place of “main strength.”
Now in passing through these works. One notices the general intelligence displayed by these men and their familiarity with the scientific principles and terms employed in their work.
After the calcining process has terminated the kilns are drawn. The ore after having gone through the process resembles in some measure unslacked limestone. The wagons are loaded with the material. Then sent along, the iron ways to the blast furnaces, which rise from the ground beneath, and whose mouths are level with the routes along which the ore ends up.
A Sad Accident
[In passing, we may advert to an accident which occurred at one of these blast furnaces only a short while ago, as investing it with melancholy interest. It was the duty of a fine young Irishman at that time to trundle these wagons to the blast furnace. He was unhappy, the worse for liquor at the time. Instead of facing the kiln and pushing the cart close up to its mouth, he turned his back to his work and gave the vehicle so violent a push that he sent it bodily into the furnace, and having got his clothes entangled in the gear, got dragged in along with it. The fire and the sulphur arising from the stove being low at the time, burnt and suffocated him to death in a few minutes].
Smelting Or Blasting
The smelting or blasting process now commences and occupies about twelve hours. The exterior of the tower or blasting furnace is pyramidal in shape, but internally it is a dome in form.
Along, with the ore, in the furnace due proportions of coke and lime were added, the former acting as the combustible agent, and lime flux. The hot air blast creates great heat to soften the ore. The ore has now melted down to a liquid. The furnace then has a Tap Hole made at the foot of it. The metal rushes out, passing along a broad mouthed gutter, in a stream of lava-like fluid, into moulds made on the floor of the pig-house.
Pig-iron Explained
In the process of ironmaking, the term “pig-iron” is one which may have puzzled not a few. Its explanation is straightforward but hardly satisfactory. The floor of the house has a thick layer of sand or loam, the moulders make one deeply indented line of about twelve feet long and named the SOW. The stream of molten metal flows down the channel. The flow diverts down several other channels. These are the PIGS. These are about three feet in length. One of the workers, blessed with an immeasurable imagination, said it was “a sow and her pigs,” and the sow has ever since given birth to pigs, or off-shoots, which are called pig-iron, pig-metal, or literally “pigs.”
Pig-iron Uses
After lying in their sandy beds for a given length of time. The pigs decline to a certain degree of coldness. They are now ready for use as pig-iron. Requiring no refining process. The quality of pig-iron” according to Chambers, to whom we are somewhat indebted here. Depends upon the nature of the ore and fuel employed. It commonly divides itself into foundry iron and forged iron. The former for castings, the latter for malleable purposes. But as we shall have to notice this part of our subject hereafter. When we shall come to the puddling process. We defer further details and proceed to speak of the auxiliaries to the blast furnaces. Namely, the hot air engines which are at work in its production.
Nielson of the Clyde Works thirty years ago discovered the hot air blast. Its superiority over the cold blast is that it consumed much less fuel and produced more metal in the process of ironmaking.
Hot Air Stoves
Well, now, stepping from the pig-houses, we pass several buildings. These are almost without aperture of any kind from top to bottom. These are the hot air stoves. Strictly adjacent are three ponderous blowing engines and a pumping engine. The latter engaged in collecting and pumping cold air into a square iron trough or receiver. From this trough, the air passes into an immensely long, iron tube. The form and circumference of which would lead the visitor to imagine. That two or three hundred robust steam engine boilers have been, riveted together. The cold air receivers are several hundreds of feet in length. From there, the air passes into the stoves of which we have spoken.
Temperature
For ironmaking, each furnace, fitted with pipes, which, while they stand perpendicular, are in the shape of an inverted horseshoe. Over these pipes, the air passes and repasses. Continually circulating until it reaches a temperature of from 500 to 600 Fahrenheit. To ascertaining the heat, a straightforward process followed. Near the foot of each hot air stove, there was a small aperture with a sliding door. When the maximum heat had been reached a piece of lead was inserted into the opening. If the heat was up to the mark, the lead metal would at once and immediately melt.
The air temperature needed to be constant. If it was too hot. The effect would be that those gases the retention of which was necessary, would be consumed in the process of smelting/ironmaking. On the other hand, if the temperature of the air was too cold, these gases would not evaporate.
